Detection rate of aneurysms was 60%

< 3 mm. 70% < 5 mm, 97% > 5 mm. Small

(2mm or less) inferiorly directed aneu-

rysms at the posterior communicating site

were most likely to be missed. Additional

information was obtained by using 2 dif-

ferent reconstruction algorithms, the

combination of which increased the ac-

curac!~ of aneurysm detection, this and

specific artifacts and pitfalls of the tech-

nique including recommended modifica-

tions to the current technique will be

discussrd.

The basis of ethanol addiction

J.I. Hubbard, N. Lin,

Neurophysiology Department,

University of Otago Medical School,

Dunedin.

Ethanol addiction is the direct cause of

much morbidity and mortality and of

great expense to individuals and to the

State. Recrnt investigations show that

there is a genetic basis to such addiction

upon which environmental events

impinge. We have been testing the

hypothesis, using a rat model, that

addiction begins with the formation of

pleasant habits and pleasant memories.

Our first experiments assessed the effect

of drugs modifying motivation and

memc,l-y upon preference for ethanol in

the presence of ethanol and water.

Ethanol intake induced by a variety of

meanr was reduced by the drug ritanserin,

an S2 berotonergic antagonist which is

thought to disinhibit the dopaminergic

reward system and by (+) Z-amino-5-

phosphonovaleric acid. a drug blocking

the NMDA synapses involved in long term

potentiation, thought to be the basis of

memory.

Anterior cervical discectomy with and without fusion.

M.K. Hunn, Neurosurgical Unit,

Dunedin Hospital, Dunedin

The operation of anterior cervical fusion

is well established. In recent years ante-

rior cervical discectomy without fusion

has been reported to produce equally

good results without the morbidity asso-

ciated with fusion.

O\er a three year period, 101 patients

underwent anterior cervical discectomy

with or without fusion for degenerative

cervix-al disc disease, in Dunedin. To compare the results of discectomy

with fusion and discectomy without fusion

a subgroup of 34 patients was studied,

consisting of all patients undergoing a

single level operation for radiculopathy

by onr sllrgeon during the 3 year period.

There were 17 patients in each group.

No significant difference in outcome or

post-operative neck pain was found be-

tween the two groups.

We conclude that anterior cervical

discectomy without fusion is a safe and

effective operation for cervical radiculo-

pathy and avoids the morbidity associated

with fusion.

Functional stereotactic thalamotomy: the Auckland Hospital experience

H.T. Lim, G. MacDonald,

Neurosurgical Unit,

Auckland Public Hospital, Auckland.

A retrospective review of 122 functional

stereotactic thalamotomy procedures per-

formed mainly for involuntary movement

disorders from 1972 to 1992 inclusive was

made. The majority, 98/ 122 (80.3%,) were

performed for the treatment of

Parkinsonian tremors uncontrolled or

poorly controlled by medication. Of the

other 24 procedures. one wzs for torti-

collis. one for dystonia musculorum

deformans. 4 for tremors secondary to

multiple sclerosis, one for thalamic pain

syndrome and the remaining 17 proce-

dures for benign essential tremors.

Eighty-nine of 119 (74.8%)) procedures

for tremors achieved excellent results, 23

of 119 (19.3%,) achievedgoodand’iof119

(5.9%) achieved poor results. Hence a

total of 112 of 119 procedures (94.1%)

achieved either an excellent or a good

outcome. 12 patients who had bilateral

thalamotomies performed. still achieved

excellent results. Frequent transient side

effects include drowsiness, confusion, in-

coordination, facial droop and dysarthria.

There were no deaths. Results in this series

using the old Hughes’ stereotactic f1-ame

and air contrast ventriculographv are as

good as other series using more modern

frames and current imaging techniqurs.

Streptococcus milleri, carious teeth, infected mouths, sinusitis and cerebral abscess

G. Martin, Department of

Neurosurgery. Wellington Hospital

StrPptococr~s millti, originating in carious

teeth, infected mouths or sinusitis WdS the

commonest cause of cerebral abscess in

Wellington during the 198Os, being re-

sponsible for 11 out of 28 intracranial abscesses (39%). It was only widely recog-

nised in the 1980s. though first described

in 1956. It lives mainly in treth, around

the gl,ms, dental root canals and throat, but also in the \ragina and faeces.

Microaerophilic, it needs CC jv for culture

Conference abstracts

and grows slowly over 48 hours. It is near]\

always penicillin sensitive but not to the

later cephalosporins.

The incidence of all tvpen of bacterial

abscess has been constant 1Or PO vears a~

about 3 per million prr veal; and .Str$. milhi incidence is about i .‘L per million

per year. Only an improvement in thr

standard of living will rCd\lce this inci-

dence, when carious teeth may brcomc

as unacceptable as chroilic discharging

ears now are.

The controversy surrounding nerve thermal injury

M. Pollock, D. Xu, NVnrn-ology Unit.

Otago Medical School. Dunedin.

Nerve thermal ill,jur-y has particular clin-

cal rrlevdnce in severely burned patients

and in the hvperthrrmic treatment of ma-

lignant dise’ase. Percutaneous fractional

thermolysis has also had a useful role in

the Treatmrllt of tic- douloureux md

hemifacial spasm. Altho@ clinically im-

portant, the physiological effects otnervc

thermal injut-irs rrmain controversial,

perhaps relatrd to an absence ofcompre-

hensive pathological studies. Wr havct

therefore undertaken ;I c,ornbined physi-

ological and morphological investigation

of localized rhernlal injtlrv to rat sciatic.

ner1.c.

LTnmvelinatrd nerve fibres showed ;I

greatrrlrlilnrl-ahilih to thermal injury, first

manifest as a rcvcrsiblr conduction block

and. at higher trmperaturcs, bv an immr-

diate and selecti\rt. axonal degeneration.

Bp contrast, lower grad? nerve thermal

injury result in a delavcd. srlective loss of

myelinated t‘ibres. E\idcncc from thiy

study suggests that this results from a heat-

ind,;ced angiopathy, inrrrlediatelyand difl

fusely manifext in I he \‘;,~a ncrvorum. ant1

giving rise to a progrc,ssi\e and ultimatrh

severr reduction in nerve blood flow. The

relative sparing ol’u~~mv~linat~d fihres is

likely a rcstllt of thrir grrater resistancr

to ischaemia.

The pathologic;tl vulnci-abilitc of

unmvelinated tibres to thermal injuI-y.

coupled with thr susceptibility of large

myrlinated ncrvc‘ fibrrs to secondarl

ischacmia. explains the previous contra-

dictions in the litrrattirc., cone-r!-rling

hyprrthermic studica.

Delayed recognition of atlanto- axial subluxation

J.N. Segelov, Neurosurgical Unit.

Roy11 Prince .Alfrrd l%ospital, Brishanr

For two yeal-s a I Y-year-old secretary con-

plainrrl of’ neck pain xitl stiffness follow-

ing a Illot~ll‘ vehicle accident.

1. Clin. Neuroscience Volume 1 Number 3 July 1994 211

Conference abstracts

Conventional X-rays and CT scans failed to demonstrate a cause. The use of high- resolution CT scanning combined with flexion/extension positioning in the scan- ner revealed atlanto-axial subluxation on movement, and subsequent surgery gave relief of the symptoms.

The same technique was employed with a 19-year-old gardener who com- plained of neck pain six months after a football injury, with increasing neck pain and stiffness on turning to the right. X-rays and CT scans showed a right sided subluxation of Cl on C2 but suggested the lesion was stable, and that surgery was not now required. The use of high resolution CT scans with flexion/extension postur- ing allowed demonstration of significant progressive subluxation, for which surgery was clearly recommended.

CIinoidal meningiomas

N. De Tribolet, CHUV, Department of Neurosurgery, 1011 Lausanne, Switzerland.

Meningiomas of the inner third of the sphenoidal ridge have been described by Cushing and others and recently reviewed by Al-Mefty under the name of clinoidal meningiomas. We report a series of 34 clinoidal meningiomas. Although CT and MRT give a good picture of the extent of these tumours, angiography is still useful in their evaluation. The most frequent feeders were the posterior ethmoidal branches of the ophthalmic artery and the sphenoidal branch of the middle meningeal. 15 tumours invaded the cav- ernous sinus and there was a participation of the inferolateral trunk and/or of the meningio-hypophyseal artery visible on the angiogram in 13 of them. Six tumours invaded the orbit and the superior orbital fissure. Complete removal of the sphen- oidal wing including the anterior clinoid and part of the planum sphenoidale al- lows early devascularization of the tumour and minimises brain retraction when as- sociated with resection of the zygomatic arch and sometimes of the superior or- bital wall. Overall, 20 tumours had a total resection and 14 a partial resection, 10 of which invaded the cavernous sinus. The most frequent post-operative complica- tion was transient CSF leak, occurring in 3 patients, 2 patients died post-operatively, and 3 suffered permanent complications. No recurrence occurred after total re- moval, but 5 patients showed signs of pro- gressive tumour growth after partial removal, treated by radiotherapy in 3 and by surgery in 2 cases. 20 patients showed pre-operative visual impairment. Out- come of vision was improved or stable in

13 (68%) and aggravated in 6 cases (32%). We suggest that progressive visual impairment should lead to aggressive sur- gical treatment.

Immunology of brain tumours

N. De Ti-ibolet, CHUV, Department of Neurosurgery, 1011 Lausanne, Switzerland.

The normal brain does not possess a lym- phatic system and is partially hidden from the systemic immune system by the BBB, furthermore brain cells do not express MHC antigens which are necessary for the initiation of an immune response. In pathological conditions however, im- munocompetent cells may find their way through transformed endothelial cells. Microglia and astrocytes may function as antigen presenting cells. Glioma cells which stimulated by cytokines such IFN can be induced to express MHC class I and class II antigens, thus making them more susceptible to an immune attack. In addition glioma cells are capable of secret- ing several cytokines including ILl, IL3 and IL6 also involved in the generation of an immune response. Indeed, a func- tional analysis of lymphocytes infiltrating gliomas has revealed the accumulation at the tumour site of cytotoxic T lymphocytes as well as NKcells. However host-immune responses against gliomas seem to be weak in comparison to other cancers. Glioma cells are known to secrete TGFBP and PGE2 which may in part be responsible for this lack of immune response, thus shielding themselves from immune attack.

In order to be recognised by the im- mune system the tumour cells must ex- press tumour associated antigens (TAA) in addition to MHC antigens, and such TAA have been identified by monoclonal antibodies (MAbs). These MAbs can be used for ‘targeted’ therapy when coupled with toxic agents or radionuclides. Pre- clinical studies have shown that, after in- travenous or intracarotid injection, there is specific accumulation of the MAb in the tumour but in insufficient amounts for therapeutic use. The relatively small amount of MAb may have a low affinity for the antigen, the BBB may hinder the passage of the MAb. Attempts have been made to overcome these drawbacks by opening the BBB for example. In addi- tion MAbs can readily be used for the treatment of carcinomatous meningitis.

There has been little success in the development of immunotherapy with IFNBl and even less with adoptive immunotherapy using LAK cells plus IL2. TIL as well as LAK cells can be expanded in vitro with IL2 and it is feasible to

reinject these cells into the tumours’ site. However the problem is that the cells re- main localized at the injection site and do not migrate actively into the tumour tis- sue. Overall augmentation of immunity requires induction of increased effector function, in addition to concomitant abatement of suppressive activities.

Basic mechanisms and cIinical

applications of neural tissue transplants

D.A. Turner, Duke University Medical Centre, Durham, USA.

The goal of neural tissue grafting is the restoration or enhancement of lesioned circuitry in the CNS. This novel form of treatment holds considerable promise for the alleviation of diseases which involve selective loss of neural subsystems, such as Parkinson’s disease, and also possibly for diseases involving abnormal function, such as acquired epilepsy. Though pre- liminary clinical studies have confirmed partial survival of transplanted fetal tissue, there remain many questions regarding the potential mechanisms of action of neural grafts, how to enhance the degree of integration of the transplanted tissue into host brain, the sources of tissue for grafting and technical aspects, such as the amount of tissue to be grafted, the proper location and evaluation concerning tissue viability and survival. I have investigated several models of neural grafting at the pre-clinical level, including Parkinsonian models at the rodent and primate level and models of acquired, temporal lobe epilepsy, with the hypothesis that circuitry restoration may be the key factor under- lying functional improvement. These in- vestigations have included anatomical and physiological evaluation of the degree of synaptic integration of the grafts into the lesioned hosts and analysis of new forms of tissue sources beyond post-mitotic fe- tal tissue. Currently, the limited supply of first-trimester human embryonic mesen- cephalic tissue (7-9 weeks) in sufficient quantity is hindering further clinical re- search for transplantation paradigms for Parkinson’s disease and thus tissue culture sources may be a critical development. The future applications of neural graft- ing may include additional diseases where a focal circuit abnormality can be identi- fied and proper tissue types to solve this abnormality can be transplanted in suff- cient quantity, including focal forms of epilepsy. These potential clinical applica- tions will require both further understand- ing of the nature of the CNS circuit abnormalities and the possible types and mechanisms of action of cellular implants.

212 J. Clin. Neuroscience Volume 1 Number 3 July 1994